The metal structures in question here are large structures having surfaces that are difficult to access for depositing an anti-corrosion paint thereon by a brush or gun. They are hollow so as to reduce the weight thereof.
This is in particular the case for the structures such as those used in the construction of the bogies or bodies of railway wagons, which comprise hollow bodies, cross-members, support beams or other sections, supporting the floors or the walls of these wagons. The field of application of the invention is of course not limited to railway transport, it being perfectly possible for any other form of transport or any other field of construction to constitute a field of application of the invention.
It is therefore difficult to protect the inside of these hollow bodies other than by the use of a bent brush or a paint spray tool, such as a specific gun or nozzle, immersion in anti-corrosion coating baths not being possible because of the size of the hollow bodies, before assembly, or of the structures that they reinforce, after assembly.
All the methods at the present time are very expensive as they are very labour-intensive and very lengthy.